Asolid aisi 302 stainless steel sphere of diameter 210 mm is coated with a 2-mm dielectric layer with a thermal conductivity 0.03 w/m·k. the sphere is suddenly quenched in a liquid at 100°c with a convective coefficient of 3500 w/m2·k . after five hours, the sphere reaches a temperature of 150°c. what was the initial temperature of the stainless steel sphere

Line joining liquid phase with liquid and solid phase mixture is known as: a) liquidus b) solidus c) tie line d) none of the mentioned

Analyze the factors that influence the choice between the following pairs of processes to make the products indicated: i) sand casting versus die casting of an electric-motor housing ii) thread rolling versus machining of a bolt for high-strength application. (co3/c5)

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.